Rotterdam-born winger Summerville joined Leeds from Feyenoord in August 2020 and the 19-year-old was handed his Whites debut in Friday night's clash against Newcastle United at St James' Park.
The Dutchman had been continually impressing for United's under-23s but says the realisation of actually stepping out for Leeds in the Premier League caused him to shed a tear.
The teen was brought on in the 67th minute for Brazilian star winger Raphinha who had picked up a hip issue as Marcelo Bielsa's side looked to bag a winner in a contest that ended in a 1-1 draw.
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"I'm very happy to have made my debut for Leeds United," said Summerville, writing on his Instagram page.
"Unfortunately no win but we go again next week.
"Words can't describe my feeling right now and as a little boy from Rotterdam south I dreamed of playing in the Premier League one day.
"My loved ones and I come from afar but I've seen nothing is impossible.
"Dreams really come true if you just believe in yourself and that man above you, good things will happen.
"I got up in the morning and I still didn't realise it happened.
"I even shed a tear because I couldn't believe when I said to my brother and cousin five years ago 'I'm going to play in the Premier League one day' and that it would really happen is a gift from god.
"For all the people, whether you're young or old, live your dream because they really come true.
"Let nothing stop you for chasing it.
"I want to thank Leeds United, the players and the staff and my loved ones for the confidence and motivation they gave me every day to be on the podium in the Premier League.
"Marching On Together."
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Thank you Laura Collins